The following studies are in progress (a) characterization of the molecular sites of androgen stimulation of protein biosynthesis in the mouse kidney. Previous studies have indicated that the concentration of polysomes is decreased after castration and increased by androgen. The cytosol also is affected and it is being fractionated into its component parts, e.g. pH 5 enzyme, transferases, for study. (b) The regulation of the concentration of the free amino acids by androgen is being extended to other species, e.g. mice, rats, marine animals and also other tissues. (c) The regulation of the metabolism of the sulfur amino acids by androgens will be undertaken to elucidate the very marked changes in hypotaurine formation in the prostate and seminal vesicles of the guinea pig after castration and androgen administration. These studies will utilize radioactively labelled compounds, the enzyme studies will be conducted in collaboration with Dr. F. Chatagner of the University of Paris.